In non-transplant patients with multiple myeloma, the pre-treatment level of clonotypic cells predicts event-free survival

The evolution of malignant and reactive γδ + T cell clones in a relapse T-ALL case after allogeneic stem cell transplantation

Background

To improve the outcome of patients with T-cell acute lymphoblastic leukemia (T-ALL), characterization of the biological features of T-ALL blast cells and the immune status of patients with T-ALL is needed to identify specific therapeutic strategies.

Findings

Using a novel approach based on the combination of fine-tiling comparative genomic hybridization (FT-CGH) and ligation-mediated PCR (LM-PCR), we molecularly identified a malignant γδ + T cell clone with a Vδ5Dδ2Jδ1 rearrangement that was paired with a T cell receptor (TCR) VγI and comprised a Vγ1Vδ5 T cell clone in a relapse T-ALL patient. This malignant Vδ5 T cell clone disappeared after chemotherapy, but the clone was detected again when disease relapsed post allogeneic hematopoietic stem cell transplantation (allo-HSCT) at 100 weeks. Using PCR and GeneScan analyses, the distribution and clonality of the TCR Vγ and Vδ subfamilies were examined before and after allo-HSCT in the patient. A reactive T cell clone with a Vδ4Dδ3Jδ1 rearrangement was identified in all samples taken at different time points (i.e., 4, 8, 68, 100 and 108 weeks after allo-HSCT). The expression of this Vδ4+ T cell clone was higher in the patient during complete remission (CR) post allo-HSCT and at disease relapse.

Conclusions

This study established a sensitive methodology to detect T cell subclones, which may be used to monitor minimal residual disease and immune reconstitution.

Frequent occurrence of highly expanded but unrelated B-cell clones in patients with multiple myeloma

Clonal diversity in multiple myeloma (MM) includes both MM-related and MM-unrelated clonal expansions which are subject to dominance exerted by the MM clone. Here we show evidence for the existence of minor but highly expanded unrelated B-cell clones in patients with MM defined by their complementary determining region 3 (CDR3) peak. We further characterize these clones over the disease and subsequent treatment. Second clones were identified by their specific IgH-VDJ sequences that are distinct from those of dominant MM clones. Clonal frequencies were determined through semi-quantitative PCR, quantitative PCR and single-cell polymerase chain reaction of the clone-specific sequence. In 13/74 MM patients, more than one dominant CDR3 peak was identified with 12 patients (16%) being truly biclonal. Second clones had different frequencies, were found in different locations and were found in different cell types from the dominant MM clone. Where analysis was possible, they were shown to have chromosomal characteristic distinct from those of the MM clone. The frequency of the second clone also changed over the course of the disease and often persisted despite treatment. Molecularly-defined second clones are infrequent in monoclonal gammopathy of undetermined significance (MGUS, 1/43 individuals or 2%), suggesting that they may arise at relatively late stages of myelomagenesis. In further support of our findings, biclonal gammopathy and concomitant MM and CLL (chronic lymphocytic leukemia) were confirmed to originate from two unrelated clones. Our data supports the idea that the clone giving rise to symptomatic myeloma exerts clonal dominance to prevent expansion of other clones. MM and second clones may arise from an underlying niche permissive of clonal expansion. The clinical significance of these highly expanded but unrelated clones remains to be confirmed. Overall, our findings add new dimensions to evaluating related and unrelated clonal expansions in MM and the impact of disease evolution and treatment on clonal diversity.